Automatic unclogging device for fluid locomotive sanding systems



V. L. FRANTZ July 15, 1969 AUTOMATIC UNCLOGGING DEVICE FOR FLUID 'LOCOMOTIVE SANDING SYSTEMS 2 Sheets-Sheet 1 Filed April 6, 1967 SA ND INVENTOR Vl/PG/L L. FRANTZ H/S ATTORNEY y 5, 1969 v. L. FRANTZ 3,455,588

AUTOMATIC UNCLOGGING DEVICE FOR FLUID LOCOMOTIVE SANDING SYSTEMS Filed April 6 1967 2 Sheets-Sheet 2 SAND INVENTOP V/RG/L L. FRANTZ Mafia/M HIS ATTORNEY United States Patent U.S. Cl. 291-3 9 Claims ABSTRACT OF THE DISCLOSURE A locomotive sanding system including a sand trap, a control valve for applying high pressure clean out and low pressure sanding air to the trap, a solenoid actuated override valve on the control valve for shifting the latter from sanding to clean out condition, a pressure responsive electrical sensing device for sensing a clogging condition in the outlet line from the sand trap and electrically actuating the solenoid valve, a mechanical valve for shutting ofi sand from the sand trap and a piston actuated by air from the solenoid valve for automatically closing the shut-01$ valve when the sensing device senses a clogging condition.

BACKGROUND OF THE INVENTION In locomotive sanding systems it has been recognized that a sand trap can be rendered inoperative by clogging of its outlet line by wet sand or otherwise and that this condition is not removed by the short duration clean out air blast applied at the beginning and usually at the end of a sanding operation. It therefore has been proposed to adapt the system to sense a clogging condition in the sand outlet line and then automatically apply a high pressure air blast for as long as necessary to remove the condition. These proposals have included automatic means for"sup posedly shutting off the flow of sand to the sand trap during the sanding operation in the realization that it is practically impossible to unclog the line in the presence of such flow, to say nothing of the waste of the limited supply of sand and air pressure by the blowing back into the sand box of the high pressure air applied for unclogging. The automatic sand shut-oflfs tried in such devices have been rubber flaps or balls inside the traps, each designed to be shifted from a normal out-of-the-way position to a position to shut off the sand inlet by the high pressure air introduced into the trap for unclogging the outlet line. However, these shut-offs which depend for actuation upon the pressure increase inside the trap, have proved impractical in extended service, with the result that the previously proposed devices for automatically sensing and removing a clogging condition in a sand outlet line have been discarded.

ABSTRACT OF THE INVENTION This invention is directed to an improved automatic unclogging device for a locomotive sanding system which is automatic in sensing and applying high pressure air to remove a clogging condition in an outlet line from a sand trap and also in positively shutting off the flow of sand into and air from the trap through the sand inlet during the unclogging. The improved device uses to shut off the sand a member that is shi-ftable between open and closed positions but, unlike prior devices, is not dependent upon air pressure in the sand trap for applying a closing force directly to the shut-oil member. Instead, the shut-off member is powered for automatic closing by an outside force which is responsive in its application to, but otherwise independent of, a pressure increase in the outlet line indicating the existence of the clogging condition. In its preferred form, the improved device uses for power air at reservoir pressure applied to a piston to which the shut-off member is mechanically connected and controlled in its application by a solenoid actuated valve which is piloted by and electrically responsive to a pressure sensitive switch in the outlet line.

With the foregoing its main objectives, other objects and advantages of the invention will appear hereinafter in the detailed description, be particularly pointed out in the appended claims, and be illustrated in the accompanying drawings in which:

FIGURE 1 is a view mainly in central vertical section of a locomotive sanding system incorporating a preferred embodiment of the automatic unclogging device of the present invent-ion;

FIGURE 2 is a fragmentary vertical sectional view taken along lines 22 of FIG. 1; and

FIGURE 3 is a side elevational view of the system with portions broken away to more clearly illustrate certain of the details of construction.

DETAILED DESCRIPTION Referring now in detail to the drawings in which like reference characters designate like parts, the improved automatic unclogging device of the present invention is adapted for use in any locomotive sanding system. Conventionally, such a system has one or more sand traps, a sand outlet line leading from each to the rails, a sand box or dome from which sand flows by gravity to each trap and a control valve for applying compressed air supplied by the locomotive reservoir or other suitable source to one or more of the traps for operating the latter. While the air is supplied to the control valve at high reservoir pressure, the usual valve is adapted to apply clean out and sanding air in sequence to any trap it controls, the clean out air as a short duration blast at reservoir pressure and the sanding air as low pressure air for carrying sand through the outlet line in the actual sanding of the traps, the clean-out air in a sanding operation at least preceding and ordinarily also following, the sanding air.

In illustrating the invention, a preferred embodiment of the improved automatic unclogging device, designated as 1, has been applied to a locomotive sanding system having a sand trap or sander 2 such as disclosed in my Patent No. 3,207,540, issued Sept. 21, 1965, the trap receiving sand by gravity from an overlying sand box, dome or other supply (not shown) open to atmospheric pressure, through a sand inlet port 3 and discharging the sand through a sand outlet port 4, the discharge being regulated by a rotatable blade 5. Air for both clean-out and sanding is supplied by an air supply pipe 6 and passes or is conducted through the trap in an air passage 7 underlying the sand chamber 8. Air issues from the passage through an air outlet port 9, which, like the sand outlet port 4, opens onto an outlet or discharge line 10 leading from the trap to the rails (not shown).

The preferred control valve 11 for controlling the application of air to the sand trap 2, is generally similar to the control valve disclosed in my Patent No. 2,589,794, issued Mar. 16, 1952. As in that patent, the illustrated control valve 11 is designed to control a pair of sand traps, for each of which it has an outlet passage 12 connected to the adjoining end of the air supply pipe 6 leading to the trap. An inlet cavity 13 constantly charged with compressed air is connectable through a central bore or valve chamber 14 to each outlet passage 12 by a pair of orifices, one a clean-out orifice 15 of a size to pass air at the applied reservoir pressure and the other a sanding orifice 16 of such cross-sectional area as to reduce the pressure of air passing through it to the usual low sanding pressure. A differential piston 17 having at one end a large head 18 against which actuating air at reservoir pressure is applied, has therebelow a pair of smaller heads or valve elements, one a lower head 19 normally blocking flow between the inlet cavity 13 and valve chamber 14 under force of a return spring 20 and the other an intermediate head 21 which, as the piston moves downwardly under the force of actuating air on its large head 18 and again upwardly under force of the return spring 20, momentarily exposes each clean-out 15 to reservoir air from the cavity 13 and causes a high-pressure blast of corresponding duration to be applied to the trap 2.

Applied to such a sanding system the improved automatic unclogging device 1 includes a positive sand shutoff 22 for shutting off or sealing the sand line between the sand box and the trap 3, against both flow of sand to and counterfiow of air from the trap, and power means responsive to a clogging condition in the outlet line for applying high pressure air for a sufficient interval to remove the condition and simultaneously closing the sand shut-off. In the preferred embodiment air at reservoir pressure is used as the power for unclogging the outlet line 10 and air at reservoir pressure also is used to close the sand shut-off 22, the air for both purposes being applied simultaneously but separately to relieve the operation of the sand shut-off from dependence upon pressure inside the trap. The preferred instrumentality for sensing the clogging condition in the outlet line 11 is a pressure sensitive switch 23, suitably of the diaphragm type, and selected to close on the excessive build-up of pressure in the outlet line 10, which inevitably occurs in a sanding operation with the line clogged or blocked.

The air at reservoir pressure for both actuating the sand shut-off 22 and applying high pressure air to the outlet line 10 conveniently is obtained by tapping the supply pipe 24 to the inlet cavity 12, with the simultaneous application of air at that pressure to the outlet line and for operating the sand shut-off devolving upon a dual function solenoid actuated valve 25. Normally closed, the solenoid valve 25 is wired in series in a circuit from a suitable electrical source with the pressure sensitive switch 23 for automatic opening upon closing of the switch in the presence of a clogging condition.

One of the functions of the solenoid valve 26 is to act 7 as an override for the control valve 11 so as to switch or shift the air passed by the latter to the trap from low pressure sanding air to the high pressure clean out air needed for the unclogging and normally obtained only momentarily from the control valve. To enable it to perform this function the solenoid valve 25 is mounted on the bottom of the housing 26 of the control valve and, when open, admits high pressure air through the lower part of a cylindrical casing 27 attached to and suspended from the bottom of the housing. A floating piston 28 in the casing has an area exposed to applied air substantially equal to that of the differential pistons large head 18. Reciprocal in the casing 27, the floating piston 28 is limited in its upward movement therein by an annular stop 29. A pusher or push-pin 30, formed as a lower extension of the stem of the differential piston, projects downwardly through the stop 29 in the differential pistons bottom or sanding position and is flush with the stop in the differential pistons clean out position. Consequently, on application of reservoir air to it by opening of the solenoid valve 25, the floating piston 28, if the differential piston 17 is then in its sanding position, will engage the pusher 30 and, with the assistance of the return spring 20, push or shift the differential piston back to clean out position. Thus, so long as actuating air is applied to both the differential piston 17 and the floating piston 28, the control valve 11, under the override of the solenoid valve 25, will apply high pressure air to the outlet line 10.

In simultaneously performing its other function, closing of the sand shut-off 22, the solenoid valve 25, on opening in response to the sensing switch 23, supplies air at reservoir pressure to an outlet line or pipe 31 connected to the casing 27 below the floating piston 28. The opposite end of the outlet line 31 connects to a preferably one way or air advance-spring return piston unit 32, the piston 33 of which is advanced by application of compressed air thereto. In turn the piston 33 is mechanically connected to the sand shut-01f 22 for closing the shut-off whenever it is advanced and returning the shut-off to open position when retracted under force of its return spring 34.

A sand shut-off 22 particularly suited for use in the improved device as positively sealing the line between the sand box and sand trap 2 against flow of sand and counterflow of air and being readily adapted for actuation by the piston unit 32, is a rotary sand shut-oif or cut-off, such as disclosed in my Patent No. 3,245,592, issued Apr. 12, 1966. As in that patent, the sand shut-off 22 has its own housing 35 mounted on the top of the sand trap 2 above the latters sand inlet port 3 and connectable at the top to a sand dome or other suitable supply (not shown). Sand enters the housing 35 through a rubber or like resilient seat 36 in the top thereof and the flow of sand through the seat is alternately permitted and prevented by an oscillating gate or blade 37 having a cylindrically convex upper face 38 wiping against a correspondingly concave underface 39 of the seat.

Legs 40 on opposite sides of the gate 37 connect it for swinging or movement in a fixed path between open and closed positions to concentric stub shafts o-r axles 41 extending through opposite sides of the housing 35 and fix ing the gates pivotal or oscillatory axis. A roll-pin or other suitable handle 42 mounted on and extending axially through one or each of the shafts 41 outside the housing 35, enables the gate 37 to be swung between open and closed position and one of these handles and a slotted head 43 on the piston 33 in which the handle is received, serve as the mechanical connection between the piston unit 32 and the sand shut-off 22.

Required to be fixed in any case to act as intended, the cylinder 44 of the piston unit 32 conveniently is formed integrally with the body 45 of the sand trap 2. With the piston unit 32 so mounted and the stroke of its piston 33 of a length to swing the gate 37 from open to closed position, sensing of a clogging condition in the outlet line 10 and the response thereto of the solenoid valve 25, will both apply high pressure air to the outlet line and close the sand shut-off 22, thus effectively preventing the influx of sand into the trap while the outlet line is being unclogged by high pressure air. Conversely, when the line is unclogged, the sensing switch 23 will open and by closing the solenoid valve 25, automatically open the sand shut-off 22 and restore the control valve 11 to condition to supply air at sanding pressure to the trap. In addition to shutting off sand during an unclogging operation, the illustrated sand shut-off will serve the same purpose during the usual intermittent cleanings of the sand trap, since the preferred roll-pin handle 42 can readily be slid axially across the shaft 41 to the point where it clears the slotted head 43 on the piston 33 so as to enable the gate 37 thereafter to be swung manually to closed position without interference by the pistons return spring 34.

From the above detailed description, it will be apparent that there has been provided an improved automatic unclogging device which in a sanding operation automatically will sense the existence of a clogging condition in an outlet line from the sand trap and both apply high pressure air to the line to remove the condition and positively shut ofl flow of sand into the trap during the unclogging. It should be understood that the described and disclosed embodiment is merely exemplary of the invention and that all modifications are intended to 'be included that do not depart from the spirit of the invention and the appended claims.

Having now described my invention, I claim:

1. In a locomotive sanding system including a sand trap having an outlet line, a sand supply for the trap, and a control valve for alternately applying high pressure clean out and low pressure sanding air to the trap, a device for automatically unclogging the outlet line comprising means responsive to a clogging condition in the outlet line for supplying high pressure air thereto to remove the condition, means for shutting off flow of sand from the supply to the trap, and means powered independently of air pressure in the trap and responsive to said clogging condition for automatically operating said sand shut-off and cutting off sand flow to the trap during application of air pressure to the outlet line to remove the clogging condition.

2. An automatic unclogging device according to claim 1, wherein the sand flows by gravity from the supply to the trap, and the sand shut-off in controlling said sand flow moves in a fixed path between open and closed positions.

3. An unclogging device according to claim 2, wherein the operating means is operatively connected to the sand shut-off and in response to a clogging condition in the outlet line automatically moves the shut-off to closed position.

4. An automatic unclogging device according to claim 3, wherein the operative connection between the operating means and the sand shut-oil is a mechanical connection.

5. An automatic unclogging device according to claim 4, including pressure sensitive means in the outlet line for sensing a clogging condition thereof, and solenoid actuated valve means responsive to said pressure sensitive means for applying high pressure air separately to the outlet line and as power to the operating means.

6. An automatic unclogging device according to claim 5, wherein the operating means is a fluid piston unit of the fluid advance-spring return type mounted exteriorly of the sand trap.

7. An automatic unclogging device according to claim 6, wherein the sand shut-off includes a housing mounted above a sand inlet leg of the trap, a gate mounted in said housing for oscillation about a fixed axis between closed and open positions, and a downwardly facing seat in said housing about a path of flow of sand therethrough to the trap and engaged by the gate in the closed position thereof for shutting oif sand flow to the trap, and the mechanical connection between the shut-off and the operating means includes a lever arm secured to a shaft of the gate and a slotted head on the piston of the fluid piston unit engaging said lever arm.

8. An automatic unclogging device according to claim 7, wherein the lever arm extends radially through and is yieldably held against axial movement in the gate shaft, whereby by shifting the lever arm axially in the shaft to the point of disengagement from the slotted piston head the gate is enabled to be moved to closed position by the lever arm for normal maintenance without interference by the fluid piston unit.

9. An automatic unclogging device according to claim 5, wherein the pressure sensitive means is a pressure sensitive electrical switch, and the solenoid actuated valve on response thereto acts on the control valve for applying therethrough high pressure air to the outlet line and separately supplies high pressure air for powering the operating means.

References Cited UNITED STATES PATENTS 2,196,977 4/1940 Campbell et a1 291-3 2,256,289 9/1941 Canetta 291-3 2,291,874 8/1942 Campbell 291-3 2,324,274 7/1943 Baldwin 29115 X 2,386,006 10/1945 Satford 291-3 2,589,794 3/1952 Frantz 251-62 2,953,248 9/1960 Troland 239-104 X 3,049,141 8/1962 Beatty et al. 137-108 3,075,318 1/1963 Dilliard et al. 51-8 3,084,484 4/1963 Hall et al. 51-8 3,103,950 9/1963 Gulick 137-494 3,359,024 12/1967 Morgan 291-3 3,375,032 3/1968 Frantz 291-3 X ARTHUR L. LA POINT, Primary Examiner HOWARD BELTRAN, Assistant Examiner US. Cl. X.R. 

